Crushed or pulverized eggshells have dozens of practical uses – as a natural calcium supplement, a coffee sweetener, a treatment for minor skin irritations, a nontoxic abrasive cleaner, or for garden compost and pest control, just to name a few.

The researchers are using microscopic eggshell particles to reinforce gelatin-based hydrogels, which then serve as stable 3D scaffolds for growing bone cells, called osteoblasts.

Camci-Unal says this technique can be applied to treat and repair bones in patients who have suffered injuries due to aging, cancer and other diseases, as well as in accidents or in combat. The 3D structure can also be used to grow not only bone for bone grafts, but also cartilage, teeth and tendons, she says.

“This is the first study that uses eggshell particles in a hydrogel matrix for bone repair,” notes Camci-Unal. “We have already filed a patent application for it earlier this year. We are very excited about our results, and we anticipate a lot of impactful applications of our invention.”

The team’s findings were released online on April 18 in the peer-reviewed journal Biomaterials Science, which is published by the Royal Society of Chemistry in the U.K. The research will also be featured on the front cover of the journal’s print edition this July.

Aside from Camci-Unal, other members of the team include Xinchen Wu, Darlin Lantigua and Sanika Suvarnapathaki, who are Ph.D. students in the Biomedical Engineering and Biotechnology program, and biology undergraduate student Stephanie Stroll.

Meeting a Worldwide Need

According to Camci-Unal, more than 2 million bone-graft procedures are performed each year worldwide. “Bone repair is crucial to restoring a patient’s functionality and self-esteem following an injury,” she says.

Photo by Edwin L. Aguirre

The researchers use a mortar and pestle to grind the eggshells into very fine powder.

However, she notes that there are limitations to existing bone-graft materials and procedures, including the risk for infection, rejection by the body’s immune system, and the limited availability of bone donors.

“Global waste of discarded eggshells typically amounts to millions of tons annually from household and commercial cooking,” says Camci-Unal. “By repurposing the eggshells, we can directly benefit the economy and the environment while providing a sustainable solution to unmet clinical needs. Despite being readily available and inexpensive, the valuable potential of eggshells in bioengineering applications remains greatly understudied.”

She says the team’s experiments demonstrate that their eggshell particle-reinforced biomaterial can significantly increase the mineralization by the bone cells compared to using hydrogels alone, resulting in faster healing. Also, since the biomaterial is combined with cells obtained from the patient and then cultured and allowed to mature in a tissue incubator before being implanted into the patient, problems of rejection by the patient’s immune system are not expected using this method, she says.

Camci-Unal points out that eggshell particles can also be incorporated easily into 3D scaffolds in a range of new biomedical applications.

Photo by Edwin L. Aguirre

The microscopic eggshell particles are used to reinforce gelatin-based hydrogels, which then serve as stable 3D scaffolds for growing bone cells, called osteoblasts."For example, our eggshell particle-reinforced scaffolds can potentially be useful in dental implants as well as in reconstructive surgeries of the skull, jaw and face,” she says. “In addition to its role in tissue regeneration, eggshell particles can also be used as a possible vehicle for delivering small molecules such as growth factors, proteins, peptides, genes and therapeutic drugs.”

Camci-Unal’s research, which is being conducted at the Saab Emerging Technologies and Innovation Center on North Campus, is currently supported by startup funds from UMass Lowell. She is in the process of applying for federal grants from the National Institutes of Health and the National Science Foundation.

This is not the first time that Camci-Unal has used unconventional raw materials to design new biomaterials for tissue engineering. In 2018, using origami (the Japanese art of paper folding) as inspiration, she and her team used plain paper to create tiny 3D scaffolds where biomaterials can grow, and then applied microfabrication techniques to engineer new tissues.